Sleep and consciousness are fundamental aspects of human psychology that affect our daily functioning and wellbeing.
Sleep cycles consist of distinct stages that repeat throughout the night. There are 4 stages of sleep plus REM sleep, each serving different biological and psychological functions. Stage 1 is light sleep where we drift in and out of consciousness. Stage 2 involves slower brain waves with occasional bursts of activity. Stages 3-4 are deep sleep states crucial for physical restoration. REM sleep, where most dreaming occurs, typically begins about 90 minutes after falling asleep. During REM, the brain is highly active while the body remains paralyzed. These stages cycle every 90-120 minutes throughout the night.
The circadian rhythm is our internal biological clock that regulates sleep-wake cycles over approximately 24 hours. It is controlled by the suprachiasmatic nucleus in the hypothalamus and influenced by melatonin, a hormone produced by the pineal gland. When circadian rhythms are disrupted by factors like shift work, jet lag, or irregular sleep schedules, it can lead to various physical and mental health issues. Circadian rhythm disruption: health consequences include increased risk of depression, anxiety, cardiovascular problems, and metabolic disorders. The rhythm responds to environmental cues called zeitgebers, with light being the most powerful. Modern lifestyle factors like artificial light, electronic devices, and irregular schedules can interfere with natural circadian patterns. Understanding and maintaining healthy sleep-wake cycles is essential for optimal physical and mental functioning. The consciousness theory of hypnosis and divided consciousness theory of hypnosis suggest that hypnotic states represent altered states of awareness where attention and perception are focused in unique ways. This relates to how consciousness shifts during different stages of sleep psychology and how the brain processes information during various states of awareness.